def has_exoplanet(readings: str) -> bool:
    lvs = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    num_readings = []
    for reading in readings:
        index = lvs.index(reading)
        num_readings.append(index)
    aver = sum(num_readings) / len(num_readings)
    # print(aver)
    # print(num_readings)
    if any(True for num_reading in num_readings if num_reading <= aver*0.8):
        return True
    else:
        return False


if __name__ == '__main__':
    print(has_exoplanet("665544554"))